Pullet unit

ABSTRACT

The present invention comprises a pulley, a shaft body which is rotatable relative to the pulley and is concentrically disposed radially inside of the pulley, a one-way clutch which is interposed at an annular space between the pulley and the shaft body, a rolling bearing which is disposed in the annular space adjacent to the one-way clutch in an axial direction, an inner annular seal which is provided outside the rolling bearing in the annular space, and an outer annular seal which is provided outside the inner annular seal and has a proximal end portion and a distal end side lip. The proximal end portion of the outer annular seal is fixed to one of an inner peripheral surface of the pulley and an outer peripheral surface of the shaft body, and the distal end side lip of the outer annular seal contacts the other peripheral surface.

BACKGROUND OF THE INVENTION

[0001] 1. [Field of the Invention]

[0002] The present invention relates to a pulley unit provided atauxiliary machines driven via a belt by a crank shaft of engine forautomobile, including a compressor for air conditioner, a water pump, analternator, and a cooling fan.

[0003] 2. [Description of the Related Art]

[0004] Various types of auxiliary machines provided at an automobileengine are driven via a belt by a crank shaft of the engine. Forexample, assuming that an alternator is coupled so as to rotatesynchronously with a crank shaft of an engine, if the rotational speedof the crank shaft is decreased, a power generating efficiency of thealternator is also decreased. Then, a pulley unit has been devised thata one-way clutch is built in a pulley portion of the alternator, whenthe rotational speed of the crank shaft is decreased, rotation of arotor of the alternator is continued by its inertial force, so that thepower generating efficiency can be improved.

[0005] A pulley unit A will be explained with reference to FIG. 11. Areference numeral 1 indicates a pulley. A reference numeral 2 indicatesa shaft body which is concentrically disposed so as to be rotatablerelative to the pulley 1. A reference numeral 3 indicates a one-wayclutch which is interposed at an annular space S between the pulley 1and the shaft body 2. Reference numerals 4 and 5 respectively indicate adeep groove ball bearing and a roller bearing that are disposed at axialdirection sides of the one-way clutch 3 in the annular space S. A belt Bis entrained about an outer periphery of the pulley 1, and the pulley 1is rotationally driven by the crank shaft of the automobile engine. Theshaft body 2 is fixed to the rotor of the alternator.

[0006] The one-way clutch 3 includes a plurality of rollers 31accommodated within a cage 32. Each roller 31 is pressed by a coilspring 33 toward a wedge-shaped narrow side (i.e., a lock side) betweena cam face 2 a and an inner peripheral surface of the pulley 1. Deepgroove bearing rings 43 and 44 are respectively formed at an innersurface of the pulley 1 and an outer surface of the shaft body 2. Thedeep groove ball bearing 4 includes a plurality of balls 41 and a cage42.

[0007] The roller bearing 5 includes a plurality of rollers 51 and acage 52. Bearing rings are directly formed at the inner surface of thepulley 1 and the outer surface of the shaft body 2. Annular seals 61 and62 are provided so as to seal the annular space S in order to preventleakage of lubricant. A metallic annular shield plate 7 is providedoutside the annular seal 62 placed at the free end side in order toprevent muddy water from entering within the annular space S.

[0008] An operation of the pulley unit A will be described. When arotational speed of the pulley 1 is relatively higher than that of theshaft body 2, the rollers 31 of the one-way clutch 3 roll toward thenarrow side of the wedge-shaped space. Thus, the pulley unit A is movedin a locked state in which the pulley 1 is integrated with the shaftbody 2 via the rollers 31 and they are rotated synchronously. When therotational speed of the pulley 1 is relatively lower than that of theshaft body 2, the rollers 31 of the one-way clutch 3 roll toward a wideside of the wedge-shaped space. Thus, the pulley unit A is moved in afree state in which transmission of rotational power from the pulley 1to the shaft body 2 is interrupted, and the shaft body 2 continues torotate only by its rotational inertial force.

[0009] In accordance with such pulley unit A, under hard circumstancesthat water enters easily when an automobile is washed at high speed by acar washer installed at a gas station or that foreign matters such asmuddy water or small stones enter easily while the automobile istraveling, it is difficult to prevent entering of such foreign mattersonly by the annular shield plate 7.

SUMMARY OF THE INVENTION

[0010] Accordingly, a main object of the present invention is to providea pulley unit which can prevent securely entering of foreign matterseven under hard circumstances that the foreign matters easily enter.

[0011] Other objects, characteristics and advantages of the presentinvention will be apparent from the following description.

[0012] The present invention can be summarized as follows.

[0013] A pulley unit of the present invention comprises a pulley, ashaft body which is rotatable relative to the pulley and isconcentrically disposed radially inside of the pulley, a one-way clutchwhich is interposed at an annular space between the pulley and the shaftbody, a rolling bearing which is provided in the annular space adjacentto the one-way clutch in an axial direction, an inner annular seal whichis provided outside the rolling bearing in the annular space, and anouter annular seal which is provided outside the inner annular seal andhas a proximal end portion and a distal end side lip. The proximal endportion of the outer annular seal is fixed to one of an inner peripheralsurface of the pulley and an outer peripheral surface of the shaft body,and the distal end side lip contacts the other peripheral surface.

[0014] In accordance with the present invention, the distal end side lipof the outer annular seal preferably includes an axial lip.

[0015] In accordance with the present invention, a peripheral groove ispreferably formed at the other peripheral surface, and the axial lip ofthe outer annular seal slide-contacts a radially inner peripheralsurface of the peripheral groove.

[0016] In accordance with the present invention, the distal end side lipof the outer annular seal includes a radial lip.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] These and other objects as well as advantages of the inventionwill become clear by the following description of preferred embodimentsof the invention with reference to the accompanying drawings, wherein:

[0018]FIG. 1 is a cross-sectional view of pulley unit relating to afirst preferred embodiment of the present invention;

[0019]FIG. 2 is a cross-sectional view of FIG. 1 along a line II-II;

[0020]FIG. 3 is an enlarged view of seal portion on the free end side ofthe pulley unit shown in FIG. 1;

[0021]FIG. 4 is an enlarged view of seal portion on the free end side ofpulley unit relating to a second preferred embodiment of the presentinvention;

[0022]FIG. 5 is a cross-sectional view of pulley unit relating to athird preferred embodiment of the present invention;

[0023]FIG. 6 is an enlarged view of seal portion on the free end side ofthe pulley unit shown in FIG. 5;

[0024]FIG. 7 is an enlarged view of seal portion on the free end side ofpulley unit relating to a fourth preferred embodiment of the presentinvention;

[0025]FIG. 8 is an enlarged view of seal portion on the free end side ofpulley unit relating to a fifth preferred embodiment of the presentinvention;

[0026]FIG. 9 is an enlarged view of seal portion on the free end side ofpulley unit relating to a sixth preferred embodiment of the presentinvention;

[0027]FIG. 10 is an enlarged view of seal portion on the free end sideof pulley unit relating to a seventh preferred embodiment of the presentinvention; and

[0028]FIG. 11 is a cross-sectional view of conventional pulley unit.

[0029] In all these figures, like components are indicated by the samenumerals.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Preferred Embodiment

[0030] A pulley unit relating to a first preferred embodiment of thepresent invention will be described with reference to FIGS. 1 through 3.A pulley unit A includes a pulley 1, a shaft body 2 which is radiallyconcentrically disposed so as to be rotatable relative to the pulley 1,a one-way clutch 3 which is interposed at an annular space S formedbetween the pulley 1 and the shaft body 2, and a deep groove ballbearing 4 and a roller bearing 5 disposed at axial direction sides ofthe one-way clutch 3 in the annular space S. The deep groove ballbearing 4 is placed at the side of accessory such as an alternator orthe like. The deep groove ball bearing 4 includes a plurality of balls41 and a cage 42. The cage 42 is formed in a crown shape having aplurality of pockets for accommodating the ball 41. Bearing rings 43 and44 for the deep groove ball bearing 4 are directly formed at an innerperipheral surface of the pulley 1 and an outer peripheral surface ofthe shaft body 2. The roller bearing 5 is disposed at the free end side.The roller bearing 5 includes a plurality of rollers 51 and a cage 52.Bearing rings for the roller bearing 5 are directly formed at the innerperipheral surface of the pulley 1 and the outer peripheral surface ofthe shaft body 2. A belt guide surface 1 a about which a belt B isentrained is formed at the outer peripheral surface of the pulley 1. Thepulley 1 is rotatably driven by a crank shaft of automobile engine. Theshaft body 2 is fixed to a rotor of alternator serving as an input shaftof accessory.

[0031] The one-way clutch 3 includes a plurality of rollers 31accommodated within the cage 32. Each of the rollers 31 is pressed by acoil spring 33 toward a wedge-shaped narrow side (i.e., a lock side)formed between a cam face 2 a formed at the outer peripheral surface ofthe shaft body 2 and the inner peripheral surface of the pulley 1. Innerannular seals 61 and 62 for preventing leakage of lubricant arerespectively provided outsides of the deep groove ball bearing 4 and theroller bearing 5 so as to seal the annular space S. An outer annularseal 8 is provided outside the inner annular seal 62 placed at the freeend side in order to prevent muddy water or the like from enteringwithin the annular space S.

[0032] The free end side inner annular seal 62 provided is configuredsuch that an outer periphery of annular core metal 63 is covered by anelastic body 64 such as a rubber or the like. The inner annular seal 62has a proximal end portion 62 a and a radial lip 62 b on the distal endside. The proximal end portion 62 a of the inner annular seal 62 isfitted into a peripheral groove 100 formed at the inner peripheralsurface of the pulley 1. The radial lip 62 b is elastically bent so asto abut the outer peripheral surface of the shaft body 2. Thus, theannular space S is sealed. The outer annular seal 8 is configured suchthat an outer periphery of an annular core metal 81 is covered by anelastic body 82 such as a rubber or the like. The outer annular seal 8has a proximal end portion 8 a, an axial lip 8 b and an auxiliary lip 8c on the distal end side. The proximal end portion 8 a of the outerannular seal 8 is fitted into a peripheral groove 22 formed at the outerperipheral surface of the shaft body 2. The axial lip 8 b engages with aperipheral groove 102 formed at the inner peripheral surface of thepulley 1, and the annular space S is sealed thereby. In other words, theaxial lip 8 b and the auxiliary lip 8 c protrude from the annular coremetal 81 toward a bearing internal direction at an incline. The axiallip 8 b is guided along a tapered surface 102 b of the peripheral groove102 toward the peripheral groove 102, and elastically slide-contacts aradially inner peripheral surface 102 a of the peripheral groove 102.The auxiliary lip 8 c is disposed so as to oppose the inner peripheralsurface of the pulley 1 with a small distance therebetween.

[0033] Similar to the outer annular seal 8, the inner annular seal 61has a proximal end portion 61 a and an axial lip 61 b on the distal endside. The proximal end portion 61 a of the inner annular seal 61 isfitted into the peripheral groove formed at the inner peripheral surfaceof the pulley 1. Then, the axial lip 61 b slide-contacts the peripheralgroove formed at the outer peripheral surface of the shaft body 2. As aresult, the annular space S is sealed.

[0034] An operation of the pulley unit A will be described.

[0035] If a rotational speed of the pulley 1 is relatively higher thanthat of the shaft body 2, the rollers 31 of the one-way clutch 3 rolltoward the narrow wedge-shaped space. Thus, the pulley 1 is integratedwith the shaft body 2 and they rotate synchronously (i.e., a lockedstate). If the rotational speed of the pulley 1 is relatively lower thanthat of the shaft body 2, the rollers 31 of the one-way clutch 3 rolltoward the wide wedge-shaped space. Transmission of rotational powerfrom the pulley 1 to the shaft body 2 is interrupted thereby, and theshaft body 2 continues to rotate only by its rotational inertial force(i.e., free state).

[0036] In a case of the above-described pulley unit A, as the annularspace S on the free end side is sealed by the inner annular seal 62 andthe outer annular seal 8 that are formed of contact type seals, it ispossible to effectively prevent foreign matters such as muddy water orthe like from entering the annular space S.

[0037] The axial lip 8 b of the outer annular seal 8 which protrudestoward the bearing internal direction at an incline slide-contacts theradially inner peripheral surface 102 a of the peripheral groove 102.Thus, if the muddy water enters, the axial lip 8 b press-contacts theradially inner peripheral surface 102 a because of pressure of the muddywater. As a result, entering of foreign matters such as muddy water orthe like can be reliably prevented. Consequently, entering of foreignmatters such as muddy water can be reliably prevented even under hardcircumstances such as high speed car washing. The outer annular seal 8seals the annular space S by the axial lip 8 b slide-contacting theradially inner peripheral surface 102 a, has a small torque and issuitable for the pulley unit A rotating at high speed.

[0038] In addition to the axial lip 8 b, by providing the auxiliary lip8 c disposed so as to oppose the opposing surface with a small distancetherebetween, an entering path for the foreign matters becomescomplicated. Further, entering of the foreign matters such as muddywater or the like can be even further prevented by a labyrinth functionof the auxiliary lip 8 c.

[0039] The outer annular seal 8 can be made by molding a resin. Further,the outer annular seal 8 can be made inexpensively as compared to aconventional annular shield plate made by polishing a metallic plate.Even if muddy water enters within the outer annular seal 8, the muddywater is moved toward the radially outerside by a centrifugal force at atime of rotational operation, and drained outside from a space betweenthe axial lip 8 b and the peripheral groove 102. In accordance with thepulley unit A, differential rotation occurs only when rotationalvariation occurs at the pulley 1. Thus, a slide speed of the outerannular seal 8 is small, and even if the axial lip 8 b slide-contactsthe pulley 1 on the outer diameter side, problems about durability ofthe outer annular seal 8 do not occur.

Second Preferred Embodiment

[0040] A pulley unit relating to a second preferred embodiment of thepresent invention will be described with reference to FIG. 4. The wholestructure of the pulley unit A relating to the second embodiment is thesame as that of FIGS. 1 and 2. In the second embodiment, an outerannular seal 9 is provided instead of the outer annular seal 8 of thefirst embodiment.

[0041] The outer annular seal 9 is configured such that an outerperiphery of an annular core metal 91 is covered by an elastic body 92such as a rubber. The outer annular seal 9 has a proximal end portion 9a and a radial lip 9 b on the distal end side. The proximal end portion9 a of the outer annular seal 9 is fitted into a peripheral groove 22formed at the outer peripheral surface of the shaft body 2. The radiallip 9 b is elastically bent to abut the inner peripheral surface of thepulley 1, so that the annular space S is sealed.

[0042] In a case of the pulley unit A relating to the second embodiment,the annular space S on the free end side is sealed by a double contacttype seal formed of the inner annular seal 62 and the outer annular seal9. Thus, entering of foreign matters such as muddy water or the like canbe reliably prevented even under hard circumstances such as high speedcar washing. The outer annular seal 9 can be made inexpensively. Even ifmuddy water enters within the outer annular seal 9, the muddy water ismoved toward the radially outerside by a centrifugal force at a time ofrotational operation, and drained outside from a space between theradial lip 9 b and the inner peripheral surface of the pulley 1.

Third Preferred Embodiment

[0043] A pulley unit relating to a third preferred embodiment of thepresent invention will be described with reference to FIGS. 5 and 6. Inaccordance with the third embodiment, the outer annular seal 8 of thefirst embodiment is mounted upside down in a radial direction. Namely,the proximal end portion 8 a of the outer annular seal 8 is fitted intothe peripheral groove 101 formed at the inner peripheral surface of thepulley 1. The axial lip 8 b engages with the peripheral groove 21 formedat the outer peripheral surface of the shaft body 2. In this way, theannular space S is sealed. The axial lip 8 b is guided within theperipheral groove 21 along a tapered surface 21 b of the peripheralgroove 21, and elastically slide-contacts a radially inner peripheralsurface 21 a of the peripheral groove 21. The auxiliary lip 8 c isdisposed so as to oppose the outer peripheral surface of the shaft body2 with a small distance therebetween.

[0044] In accordance with the pulley unit A of the third embodiment, asin the first embodiment, the annular space S on the free end side issealed by a double contact type seal formed of the inner annular seal 62and the outer annular seal 8. Consequently, even under hardcircumstances such as high speed car washing, entering of foreignmatters such as muddy water can be reliably prevented. The outer annularseal 8 can be made inexpensively. The outer annular seal 8 has a smalltorque and is suitable for high speed rotating pulley unit A. Inaddition to the axial lip 8 b, by providing the auxiliary lip 8 cdisposed so as to oppose the opposing surface with a small distancetherebetween, an entering path for the foreign matters becomescomplicated. Further, entering of the foreign matters such as muddywater can be even further prevented by a labyrinth function of theauxiliary lip 8 c. When the pulley unit A is rotated at high speed, theaxial lip 8 b protruding in a bearing internal direction at an inclinedeflects by a centrifugal force in a direction for press-contacting theradially inner peripheral surface 21 a (i.e., direction indicated by thearrow P), so that entering of muddy water can be prevented.

Fourth Preferred Embodiment

[0045] A pulley unit relating to a fourth preferred embodiment of thepresent invention will be described with reference to FIG. 7. The wholestructure of the pulley unit A of the fourth embodiment has the same asin the first embodiment. In accordance with the fourth embodiment, theouter annular seal 9 of the second embodiment is mounted upside down ina radial direction. The proximal end portion 9 a of the outer annularseal 9 is fitted into the peripheral groove 101 formed at the innerperipheral surface of the pulley 1. The radial lip 9 b is elasticallybent to abut the outer peripheral surface of the shaft body 2. In thisway, the annular space S is sealed.

[0046] In accordance with such pulley unit A, the annular space S on thefree end side is sealed by a double contact type seal formed of theinner annular seal 62 and the outer annular seal 9. Thus, entering offoreign matters such as muddy water can be reliably prevented even underhard circumstances such as high speed car washing. The outer annularseal 9 can be made inexpensively.

Fifth Preferred Embodiment

[0047] A pulley unit relating to a fifth preferred embodiment of thepresent invention will be described with reference to FIG. 8. The wholestructure of the pulley unit A of the fifth embodiment is the same asthat of FIGS. 1 and 2. In accordance with the fifth embodiment, an outerannular seal 10 is provided outside the inner annular seal 62. The outerannular seal 10 is configured such that an outer periphery of an annularcore metal 11 is covered by an elastic body 12 such as a rubber. Theouter annular seal 10 has a proximal end portion 10 a, an axial lip 10 band an auxiliary lip 10 c on the distal end side. A peripheral groove103 is formed by cutting away in a curved concave shape from the innerperipheral surface of the pulley 1 to the outside surface thereof Theproximal end portion 10 a of the outer annular seal 10 is fitted into,by pressing, the peripheral groove 23 formed at the outer peripheralsurface of the shaft body 2. The axial lip 10 b engages with theperipheral groove 103. In this way, the annular space S is sealed. Theaxial lip 10 b elastically slide-contacts the peripheral groove 103, andthe auxiliary lip 10 c is disposed so as to oppose the inner peripheralsurface of the pulley 1 with a small distance therebetween. A grooveportion 10 d having a triangular cross-section is formed at the outerdiameter side outer surface of the outer annular seal 10 by radiallyextending the tapered surface.

[0048] In accordance with such pulley unit A, the same effects as in thefirst embodiment can be obtained.

[0049] Even if the outer annular seal 10 receives a centrifugal force byhigh speed rotation, the proximal end portion 10 a on the inner diameterside is not deformed and the auxiliary lip 10 c is deflected toward theouter diameter side. Thus, the axial lip 10 b press-contacts theperipheral groove 103 and a sealing effect can be maintained.

[0050] The peripheral groove 103 is formed in a curved concave shape atan incline from the inner peripheral surface of the pulley 1 to theoutside surface thereof. The groove portion 10 d is formed at the outersurface of the outer annular seal 10 by radially extending the taperedsurface. Thus, muddy water at the inner and outer surfaces of the outerannular seal 10 is smoothly drained outside by a centrifugal force at atime of high speed rotation through the peripheral groove 103 and thegroove portion 10 d. The groove portion 10 d needs not to be formed soas to have a triangular cross-section. For example, the groove portion10 d may be formed in a radially curved concave shape. The peripheralgroove 103 may not be formed in a curved concave shape, and may have alinear inclined surface.

Sixth Preferred Embodiment

[0051] A pulley unit relating to a sixth embodiment of the presentinvention will be described with reference to FIG. 9. The sixthembodiment relates to a modified example of the outer annular seal 10 ofthe fifth embodiment. A bent portion 11 a is formed at the proximal endportion 10 a of the outer annular seal 10 by bending the annular coremetal 11 in a bearing internal direction. According to the pulley unit Awith such structure, the same effects as in the fifth embodiment can beobtained. As the bent portion 11 a is formed at the annular core metal11, a strength of the outer annular seal 10 is improved and a strengthof fixing the outer annular seal 10 to the shaft body 2 is alsoimproved.

Seventh Preferred Embodiment

[0052] A pulley unit relating to a seventh preferred embodiment of thepresent invention will be described with reference to FIG. 10. Theseventh embodiment relates to a modified example of the outer annularseal 10 of the fifth embodiment. The bent portion 11 a is formed at theannular core metal 11. Further, an extending portion 12 a is formed atthe proximal end portion 10 a by extending the elastic body 12 in aninner diameter direction. An annular concave portion 24 having a reduceddiameter in a radially internal direction is formed at the outer end ofthe peripheral groove 23. According to the pulley unit A, the sameeffects as in the sixth embodiment can be obtained. By the extendingportion 12 a, it is possible to prevent muddy water from entering from aspace between the proximal end portion 10 a of the outer annular seal 10and the peripheral groove 103.

[0053] In the respective embodiments, the deep groove ball bearing 4 isdisposed at the accessory side of the one-way clutch 3, and the rollerbearing 5 is disposed at the free end side thereof. Nevertheless, thepresent invention is not limited to the pulley unit A with suchstructure, and may be applied to various types of pulley units. The freeend side may not be sealed by a double contact type seal, and theaccessory side may be sealed by a double contact type seal.Alternatively, opposite ends of the annular space S may be sealed by adouble contact type seal.

[0054] Instead of the outer annular seals 8 and 10 having the axial lips8 b and 10 b and the auxiliary lips 8 c and 10 c, respectively, an outerannular seal that is formed only of the axial lip 8 b or 10 b and doesnot have the auxiliary lip 8 c or 10 b may be used.

[0055] Although outer rings and inner rings of the bearings and theone-way clutch are integrally formed with the pulley and the shaftrespectively in the pulley units described above, all or part of themcan be formed separately. For example, when the outer ring and innerring the bearing are formed separately, the outer annular seal can befixed on pulley or shaft and the inner annular seal can be fixed on theouter ring or the inner ring of the bearing, or the outer annular sealand the inner annular seal can be fixed on the pulley or shaft, or theouter annular seal and the inner annular seal can be fixed on the outerring or the inner ring of the bearing.

[0056] While there has been described what is at present considered tobe preferred embodiments of this invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and scope of this invention.

What is claimed is:
 1. A pulley unit comprising: a pulley; a shaft bodywhich is rotatable relative to said pulley and is concentricallydisposed radially inside of said pulley; a one-way clutch which isinterposed at an annular space between said pulley and said shaft body;a rolling bearing which is disposed in said annular space adjacent tosaid one-way clutch in an axial direction; an inner annular seal whichis provided outside said rolling bearing in said annular space; and anouter annular seal which is provided outside said inner annular seal andhas a proximal end portion and a distal end side lip, wherein theproximal end portion of said outer annular seal is fixed to one (i.e., afirst peripheral surface) of an inner peripheral surface of said pulleyand an outer peripheral surface of said shaft body, and the distal endside lip of said outer annular seal contacts the other peripheralsurface (i.e., a second peripheral surface).
 2. The pulley unitaccording to claim 1, wherein the distal end side lip of said outerannular seal includes an axial lip.
 3. The pulley unit according toclaim 2, wherein said second peripheral surface is provided with aperipheral groove, and said axial lip of said outer annular sealslide-contacts a radially inner peripheral surface of said peripheralgroove.
 4. The pulley unit according to claim 1, wherein the distal endside lip of said outer annular seal includes an axial lip and anauxiliary lip.
 5. The pulley unit according to claim 4, wherein saidsecond peripheral surface is provided with a peripheral groove, saidaxial lip of said outer annular seal slide-contacts the radially innerperipheral surface of said peripheral groove, and said auxiliary lipopposes said second peripheral surface with a small distancetherebetween.
 6. The pulley unit according to claim 1, wherein thedistal end side lip of said outer annular seal includes a radial lip. 7.A pulley unit comprising: a pulley; a shaft body which is rotatablerelative to said pulley and is concentrically disposed radially insideof said pulley; a one-way clutch which is interposed at an annular spacebetween said pulley and said shaft body; a rolling bearing which isdisposed in said annular space adjacent to said one-way clutch in anaxial direction; an inner annular seal which is provided outside saidrolling bearing in said annular space and has a proximal end portion anda distal end side radial lip; and an outer annular seal which isprovided outside said inner annular seal in said annular space and has aproximal end portion and a distal end side lip, wherein the proximal endportion of said inner annular seal is fixed to one (i.e., a firstperipheral surface) of an inner peripheral surface of said pulley and anouter peripheral surface of said shaft body, the distal end side lip ofsaid outer annular seal contacts the one peripheral surface, theproximal end portion of said outer annular seal is fixed to the otherperipheral surface (i.e., a second peripheral surface) and the distalend side radial lip of said inner annular seal contacts the otherperipheral surface.
 8. The pulley unit according to claim 7, whereinsaid distal end side lip of said outer annular seal includes an axiallip and an auxiliary lip, a peripheral groove is provided at said firstperipheral surface, said axial lip slide-contacts a radially innerperipheral surface of said peripheral groove, and said auxiliary lipopposes said first peripheral surface with a small distancetherebetween.
 9. The pulley unit according to claim 7, wherein saiddistal end side lip of said outer annular seal includes a radial lip.10. A pulley unit comprising: a pulley; a shaft body which is rotatablerelative to said pulley and is concentrically disposed radially insideof said pulley; a one-way clutch which is interposed at an annular spacebetween said pulley and said shaft body; a rolling bearing which isdisposed in said annular space adjacent to said one-way clutch in anaxial direction; an inner annular seal which is provided outside saidrolling bearing in said annular space and has a proximal end portion anda distal end side radial lip; and an outer annular seal which isprovided outside said inner annular seal in said annular space and has aproximal end portion and a distal end side lip, wherein the proximal endportions of said inner annular seal and said outer annular seal arefixed to one (i.e., a first peripheral surface) of an inner peripheralsurface of said pulley and an outer peripheral surface of said shaftbody, and the distal end side radial lip of said inner annular seal andthe distal end side lip of said outer annular seal contact the otherperipheral surface (i.e., a second peripheral surface).
 11. The pulleyunit according to claim 10, wherein said distal end side lip of saidouter annular seal includes an axial lip and an auxiliary lip, aperipheral groove is provided at said second peripheral surface, saidaxial lip slide-contacts a radially inner peripheral surface of saidperipheral groove, and said auxiliary lip opposes said second peripheralsurface with a small distance therebetween.
 12. The pulley unitaccording to claim 10, wherein said distal end side lip of said outerannular seal includes a radial lip.
 13. A pulley unit comprising: apulley; a shaft body which is rotatable relative to said pulley and isconcentrically disposed radially inside of said pulley; a one-way clutchwhich is interposed at an annular space between said pulley and saidshaft body; a rolling bearing which is disposed in said annular spaceadjacent to said one-way clutch in an axial direction; an inner annularseal which is provided outside said rolling bearing in said annularspace and has a proximal end portion and a distal end side radial lip;and an outer annular seal which is provided outside said inner annularseal in said annular space and has a proximal end portion and a distalend side lip, wherein the proximal end portion of said inner annularseal is fixed to one (i.e., a first peripheral surface) of an innerperipheral surface of said pulley and an outer peripheral surface ofsaid shaft body, and the proximal end portion of said outer annular sealis fixed to the other peripheral surface (i.e., a second peripheralsurface), the distal end side lip of said outer annular seal has anaxial lip and an auxiliary lip, said axial lip engages with an innerperipheral surface of peripheral groove formed at said first peripheralsurface and said auxiliary lip opposes said first peripheral surfacewith a small distance therebetween.
 14. The pulley unit according toclaim 13, wherein the inner peripheral surface of said peripheral grooveis inclined in a curved concave shape, and a tapered groove is formedwith an outer surface of said outer annular seal being tapered in aradial direction.
 15. The pulley unit according to claim 13, whereinsaid outer annular seal includes an annular core metal and an elasticbody covering an outer periphery of said annular core metal, and aradially inner end of said annular core metal is bent inside along saidsecond peripheral surface.
 16. The pulley unit according to claim 13,wherein said outer annular seal includes an annular core metal and anelastic body covering an outer periphery of said annular core metal, anannular concave portion formed by reducing a diameter of outer end ofsaid second peripheral surface in a radially internal direction isprovided, and a radially inner end of said elastic body of said outerannular seal is fitted into said annular concave portion.